Adding OpenWrt support for Mercusys D121G

Hi. I got myself under 30$ new router product details page https://service.mercurycom.com.cn/product-465-2.html ) and i do not see it under https://openwrt.org/supported_devices section.
Mediatek MT7620DA - main chipset
Realtek RTL8367S - LAN\WAN
Mediatek MT7613BEN - AC WIFI

We also need to know the flash chip model

do you have UART to USB serial adapter?

The original flash is 32 m, has been in 64 m brush TP Archer cc-link C5 v4 normal no 5 g signal

32 mega bits = 4 MB

if you can, open the case and record the model of the flash chip

the flash chip is the black one between the AC WIFI chip and the white antenna wire

it has 4 pins on each side = 8 total pins and labeled U3 on the board

I cannot read it

Have the query to upload

I still cant read it

Probably it is 4 MB and too small for openwrt

This is before, I have change for 8 m can run TP cc-link Archer C5 v4 version of openwrt but no 5 g signal

Oh you changed the flash chip ok

post the kernel log

5 g is no drive MT7613, but TPLINK C5 v4 is MT7612

mt7615 and mt7613 uses same firmware

DEVICE_PACKAGES must have these for MT7613

kmod-mt7615e
kmod-mt7615-firmware

I installed opkg install kmod-mt7615e and kmod-mt7663-firmware-ap no success can't install


and

Does not contain the driver

the packages are

kmod-mt7615e
kmod-mt7663-firmware-ap

do not use opkg install

build a new image with these selected

Where I can't over the wall, unable to compile successfully.

Can be cloned to the source code to compile a firmware contains the driver let me use.